The Crustose Brown Algae of New Zealand: a Taxonomic Study

Abstract:

Nine species of crustose brown algae are described from New Zealand’s coast. Three species
are microthalli of species of Scytosiphonaceae: Colpomenia bullosa Yamada, Scytosiphon
lomentaria (Lyngbye) Link and Petalonia binghamiae (J. Agardh) Vinogradova. One species
of Lithodermataceae, Pseudolithoderma roscoffense Loiseaux is described from Northland.
Four species are Ralfsiaceae, Ralfsia expansa (J. Agardh) J. Agardh, Ralfsia confusa
Hollenberg, a new species, Ralfisa sp. “smooth”, and Hapalospongidion gelatinosum
Saunders. H. saxigenum Lindauer is identical to Hapalospongidion gelatinosum Saunders.
One new species of Diplura, currently placed in the Ralfsiaceae, is described. Ralfsia
verrucosa (Areschoug) Areschoug, previously reported from New Zealand, was not found.
ITS-2 sequences show that Ralfsia expansa, Ralfsia confusa and Ralfsia sp. “smooth” are
closely related. Ralfsia expansa is more distantly related. These relationships are consistent
with morphological differences.
LSU nrDNA sequences show Diplura sp. and Pseudolithoderma roscoffense are not closely
related to other Ralfsiaceae. These algae form a weakly supported group with members of the
Sphacelariales. Hapalospongidion and three Ralfsia species form a well supported group, but
this group’s relationship to other phaeophycean orders is not resolved. These results are
discussed in relation to plastid number and the status of the order Ralfsiales.